Research On Ultrasonic Vibration Aided Riveting Technology For Titaniu-Alloy Rivet

With the increasing use of composite materials and titanium-alloy in the aircraft structure,the titanium-alloy rivets are applied more and more extensively.There are some disadvantages in the existing rivet connectting technology for titanium-alloy rivet,such as automatic riveting and electromagnetic riveting.Ultrasonic vibration is widely used in the processing of material which is difficult to be formed.It can improve rheological behavior,reduce yield strength and enhance plastic limit.In this paper,ultrasonic vibration is applied to traditional pressure riveting process,and the impact on the deformation of titanium-alloy rivets is researched by simulation and experiment.The main contents of this paper include the following aspects:1)The riveting platform based on ultrasonic vibration is designed,which emphatically analyzes selection principle of transducer and luffing mechanism.Through the analysis of modal and harmonic response,the ultrasonic vibration device can obtain larger longitudinal amplitude under 20 k Hz.2)The effect of ultrasonic vibration on the material plastic deformation is discussed.The stress-strain relationship of titanium-alloy rivet under static and ultrasonic vibration aided can be obtained by experiments,which indicates that ultrasonic vibration can reduce the yield strength.And microstructure observation shows that the material can keep its original organization with the help of ultrasonic vibration.3)Through the simulation analysis,ultrasonic vibration can reduce pressure riveting force by 20%,and the effect will enhance with the increase of ultrasonic vibration amplitude.The critical rate of riveting aided by ultrasonic vibration can be obtained through the analysis of surface effect.Through the simulation research,ultrasonic vibration can improve the accurate control of the heading-height by reducing the rebound.4)The experiments of ultrasonic vibration aided riveting are developed.Comparing the experimental data,the error of simulation analysis is less than 6%,which can verify the feasibility of simulation research.The experiments of interference distribution with specific heading-height show that it can get more uniform distribution and larger interference along the rivet's axis direction.Through the comparative experiments on the control of heading-height and riveting force,the optimal parameters for interference quantity can be obtained.The riveting technology based on ultrasonic vibration reduces the riveting fore and improves the riveting interference distribution on riveted structure.This method provides new technical means to solve the connection problem of the refractory rivets material.